1. Field of the Invention
The present invention is directed to a hydrodynamic coupling arrangement, in particular a torque converter, comprising a housing be coupled to a driveshaft having an impeller, a turbine wheel arranged in an interior space of the housing driven by the impeller, and a first damper arrangement by which the housing can be coupled to a driven member by a lockup clutch. The first damper arrangement comprises a first torsional vibration damper having a first primary side connected to the lockup clutch and a first secondary side which is rotatable with respect to the first primary side around an axis of rotation against the action of a first damper spring arrangement, and comprising a second torsional vibration damper having a second primary side connected to the first secondary side of the first torsional vibration damper and a second secondary side rotatable with respect to the second primary side around the axis of rotation against the action of a second damper spring arrangement. The turbine wheel is connected to an intermediate torsional vibration damper region comprising the first secondary side and the second primary side.
2. Related Art
A hydrodynamic coupling arrangement of the kind mentioned above is used as component of the powertrain of a motor vehicle and is employed therein for coupling the engine to the transmission. When the lockup clutch is open, torque can be transmitted along a first torque transmission path from the engine via the impeller, the turbine wheel and the second torsional vibration damper to the driven member and from there to the transmission. A second torque transmission path along the closed lockup clutch and the first and second torsional vibration dampers serves to bypass the first torque transmission path so as to prevent friction losses in the hydrodynamic circuit generated by the impeller.
Rotational irregularities occurring in operation can excite vibrations in the powertrain which in turn result, for example, in the occurrence of rattling noises in the passenger compartment of the motor vehicle. Therefore, the effort is made to counteract the excitation of vibrations of this kind by providing dampers. For this purpose, the first torsional vibration damper and second torsional vibration damper are provided in the second torque transmission path between the lockup clutch and the driven member. The turbine wheel is coupled to the intermediate torsional vibration damper region so as to be fixed with respect to rotation relative to it so that the second torsional vibration damper also acts as a damper in the first torque transmission path.
Torsional vibration dampers dampen occurring vibrations within a broad frequency range. However, the rotational irregularities occurring in the powertrain are not uniformly distributed, but rather have orders of excitation which are related, for example, to the firing frequency of the engine. In engines which are optimized with respect to CO2 emissions and which generate greater rotational irregularities compared to conventional engines, certain excitation orders can no longer be damped satisfactorily by torsional vibration dampers.